A chemical used to make rocket fuel that’s particularly toxic to children has been found in all samples of women’s breast milk tested throughout the United States, Texas Tech University scientists say.

Percholorate, which is used mostly at defense industry plants, was detected in women’s breast milk at levels five times greater than had been found in cow’s milk, researchers at the school’s Institute of Environmental and Human Health said.

Breast milk from 36 women in 18 states was sampled, and traces of the chemical were found in each one, the Los Angeles Times reported.

Previous studies detected the chemical in cow’s milk and other food products. While toxic to all humans, perchlorate impairs thyroid hormone production that’s necessary for normal brain and cellular development among infants and children, the newspaper said.

As a precaution, the researchers recommended that pregnant and nursing women block the effects of the chemical by taking iodine supplements, the Times said.

At the levels detected in the study, a 1-month-old infant would ingest enough of the chemical to exceed the limit suggested last week by the U.S. Environmental Protection Agency. The same limit of 24.5 parts per billion also was recommended last month by the National Academy of Sciences. Currently, there is no enforced national standard, the newspaper said.

The researchers’ findings are reported on the Web site of the journal Environmental Science and Technology, a peer-reviewed publication of the American Chemical Society.